GOTO not going to...

[StuartT]

Last night, I polar aligned my mount (EQ6R Pro and Synscan) then did a two star alignment on Capella and Markab. But then went I selected Jupiter as a target, it was miles off! Similarly when I asked it to go to M31. A good 10 - 15 degrees out in both cases. Jupiter ain't such a biggy as I could use my finder scope to get that. But surely GOTO should be more accurate than that?

So I parked the scope, switched off and started all over again. Double checking I'd entered the right date and time. Still the same problem.

How can Synscan be so far off?

[malc-c]

Stu, this seems to be a common issue for some reason or another

same here

 

[spikkyboy]

My CPC had GPS software issue, im getting the same (also Jupiter) with my HEQ5PRO. I polar aligned, did a 2 star and goto jupiter was miles off. The RA was spot on but DEC about 10 degrees too low. Weird. and also very frustrating. Im also using the SW gps mouse.

[StuartT]

16 hours ago, malc-c said:

Stu, this seems to be a common issue for some reason or another

same here

 

Hmm... interesting

3 hours ago, spikkyboy said:

My CPC had GPS software issue, im getting the same (also Jupiter) with my HEQ5PRO. I polar aligned, did a 2 star and goto jupiter was miles off. The RA was spot on but DEC about 10 degrees too low. Weird. and also very frustrating. Im also using the SW gps mouse.

Yes. Same thing. RA looked about right but Dec was off by miles.

Wasn't just Jupiter tho, happened with M31 also

[Shimrod]

16 hours ago, malc-c said:

Stu, this seems to be a common issue for some reason or another

same here

 

I am not sure two cases on two different (although same brand) mounts makes it a common issue. I've just had a search across Cloudy Nights forum (and the wider internet!) to see if there are any recent reported incidences there of Skywatcher mounts failing to 'goto', without success. I couldn't find any, so this is probably just co-incidence - unless it is a bug in calculations that is only affecting specific geographic locations - Celestron had a bug in the Skyportal module earlier this year that only affected parts of Europe.

[StevieDvd]

Your PA is independent of the Synscan operation as it's a physical setting of the hardware, so if you have this set roughly correct we can check a few things manually.

Power up the mount and set you date/time/location/dst as you normally do.  I would recommend flipping the DST setting to No and back to Yes to make sure that gets correctly noted by the handset.

Choose a 1 star alignment and move the star a little in the view, accept the alignment even if not centered.

Then release the clutches and manually align the star and re-tighten the clutches. This should fool the mount that it found the star based on your inputs be they right or wrong.

Then do a few gotos and see if they are about right.  If OK then park the mount and switch off,  without moving anything power on and restart your normal procedure.

What the above does is :

• Set an accurate home position for the mount to start from.
• Reduces/avoids the alignment adjustments recorded by the handset
• If gotos fail either PA is off or there is an issue with the mount not moving as expected.

Hopefully some of that might trigger what the cause is, if it still happens.

 

[Louis D]

It boggles my mind that my ancient (90s vintage) Sky Commander DSC can do a bang-on two star alignment every time without leveling, polar alignment, or geo location.  Date is only need for solar system objects.  Objects are always within a few degrees with rough initial alignment that I then refine with "realign on object" for each centered object.  Modern DSCs should be miles ahead of it by now in accuracy.  Can you realign on an object once you center Jupiter or M31 and get good gotos after that?

[wookie1965]

I always polar align without weights and ota but I then check it again when loaded up. I find when starting off forget the star alignment goto a bright star centre it by pressing back once then back again but hold it, it will then flash up centre object always finish with left and up on the handset (Helps with backlash) leave it tracking then goto another star or object at the moment Saturn and Jupiter make ideal candidates centre that object like before. 

 

Now without moving the scope go in and do a two star alignment the mount knows where it is already the first star will be off but not by much the second will be even closer in the FOV after that goto a known object. 

 

I have found this to be the work around for the mounts idiosyncrasies usually everything is either dead centre or really close but definitely in the FOV.

[Jiggy 67]

Before looking at the software, there are three mechanical issues to check and rule out:

It helps if your PA is as accurate as possible. Many will disagree with this but I have been using Synscan and EQ6 R Pro for a few years and I am 100% certain it makes for more accurate pointing 

An accurate home position is crucial. There are videos to assist with this.

Use alignment stars on the same side of the meridian as your targets. If you Star align on one side of the meridian and then slew to a target on the other side, you may suffer from cone error which skews the pointing accuracy. If you do suffer from cone error, you can compensate for this with a three star alignment, the third star being on the opposite side of the meridian from your first two……This is actually the only purpose of a three star alignment, the third star has no other purpose other than to compensate for cone error